JP2024092853A - Manufacturing method of hydrated solidified body and manufacturing method of slag roadbed material - Google Patents

Abstract

The present invention provides a method for producing a hydrated solidified material, which can easily produce a hydrated solidified material even in a small space, and a method for producing a roadbed material from the hydrated solidified material, and a method for producing a slag roadbed material.
[Solution] The method for producing a hydrated solid according to the present invention includes a mixing step of mixing steelmaking slag, water, and a binder to produce a mixture, and a molding step of putting the produced mixture into a molding machine and molding it to obtain a hydrated solid.
[Selected Figure] Figure 1

Description

The present invention relates to a method for producing a hydrated solidified body and a method for producing a slag roadbed material.

In steelworks, steelmaking slag generated during molten iron pretreatment, converters, or secondary refining processes is generally crushed and magnetically separated, and then subjected to appropriate processing before being used as roadbed material or soil improvement work materials. However, in the particle size distribution after crushing and magnetic separation, fine-grained steelmaking slag that is too fine for the particle size standards for the intended use cannot be used as roadbed material or other applications as it is, and the processing of fine-grained steelmaking slag has been an issue for many years.

In order to solve this problem, a method has been proposed in recent years in which a mixture of steel slag, cement, water, etc. is solidified to produce a hydrated solid, which is then crushed to use the crushed particles as roadbed material. For example, Patent Document 1 proposes a method for producing a hydrated solid by casting a mixture containing steel slag on flat ground, in which notches are made in the mixture when it is cast to improve the yield rate during crushing, allowing the hydrated solid to be used efficiently as roadbed material.

Japanese Patent No. 5375358

In the method disclosed in Patent Document 1, when producing a hydrated solid, the kneaded material must be poured into a raw material yard and solidified, and a large space is required for mass production of hydrated solids. In addition, in the method of Patent Document 1, the kneaded material is crushed by cutting it, so it is necessary to secure manpower and heavy machinery, and since there is an appropriate time range for cutting the kneaded material, it is necessary to spend a lot of time and money on production management. Furthermore, due to the nature of the material to be poured, the mixture ratio of steel slag in the kneaded material is basically about 70 to 75 mass%, and the remaining 25 to 30 mass% is water and cement, which do not actually need to be processed, and there is a problem that extra costs are incurred in production and handling.

The present invention has been made in consideration of the above problems, and aims to provide a method for producing hydrated solidified bodies that can be easily produced even in a small space and that can produce roadbed material from the hydrated solidified bodies, and a method for producing slag roadbed material.

The present invention which solves the above problems is as follows.
[1] A kneading step of kneading steelmaking slag, moisture, and a binder to prepare a kneaded mixture;
a molding step of putting the prepared kneaded mixture into a molding machine and molding it to obtain a hydrated solidified body;
A method for producing a hydrated solidified body comprising the steps of:

[2] The method for producing a hydrated solidified body described in [1] above, wherein the moisture content of the kneaded material is in the range of 10% by mass or more and 14% by mass or less.

[3] The kneaded product is a mixture of ground granulated blast furnace slag as the binder and cement that promotes hardening of the ground granulated blast furnace slag,
The method for producing a hydrated solidified body according to the above [1] or [2], wherein the mixing ratio of the cement in the kneaded mixture is in the range of 2 mass % or more and 14 mass % or less.

[4] The method for producing a hydrated solid described in any one of [1] to [3] above, in which the mixing ratio of the steelmaking slag in the kneaded mixture is in the range of 80 to 88 mass %.

[5] The method for producing a hydrated solidified body according to any one of [1] to [4] above, further comprising a curing step of curing and drying the hydrated solidified body obtained in the molding step.

[6] A crushing step of crushing the hydrated solidified body produced by the method for producing the hydrated solidified body according to any one of [1] to [5] above into crushed particles;
A particle size adjusting step of adjusting the crushed particles to a required particle size to obtain a slag roadbed material;
A method for producing a slag roadbed material comprising:

According to the present invention, it is possible to easily produce a hydrated solidified body even in a small space, and to produce slag roadbed material from the hydrated solidified body.

FIG. 2 is a diagram showing the flow of a method for producing a hydrated solidified material and a method for producing a roadbed material according to the present invention. 1 is a bird's-eye view image of a hydrated solidified material produced according to the present invention. 1 is a side view of a hydrated solid produced according to the present invention. FIG. 2 is a graph showing the particle size distribution of crushed particles obtained by crushing the hydrated solidified body of Blend 1 using a crusher and the particle size distribution of the steelmaking slag used to produce the hydrated solidified body. FIG. 2 is a graph showing the particle size distribution of a slag roadbed material produced using a hydrated solidified body of Mixture 1.

(Method for producing hydrated solidified body)
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a flow of a method for producing a hydrated solidified material and a slag road base material according to the present invention.

The method for producing a hydrated solid according to the present invention includes a kneading step in which steelmaking slag, water, and a binder are mixed to produce a mixture, and a molding step in which the mixture is placed in a molding machine and molded to obtain a hydrated solid.

(1) Mixing process First, the steelmaking slag, water, and binder are mixed to prepare a mixture (mixing process). For this purpose, the steelmaking slag, binder, and water are prepared. It is preferable to mix an alkali stimulant that accelerates the hardening of the binder together with the steelmaking slag, water, and binder, as necessary.

Steelmaking slag is used as aggregate for hydrated solidified bodies. As steelmaking slag, molten pig iron dephosphorization slag (pretreatment slag) produced in molten pig iron pretreatment, converter slag produced in a converter, casting slag (cast slag) discharged after casting, etc. can be used after confirming that they do not expand. In the present invention, fine-grained steelmaking slag can be solidified well to produce hydrated solidified bodies. Specifically, for example, hydrated solidified bodies can be produced well using steelmaking slag with a grain size of about 0-5 mm. Note that 0-5 mm steelmaking slag is under-sieve steelmaking slag classified using a sieve with 5 mm mesh.

Moisture is used to adjust the hydration reaction of the binder and the fluidity of the kneaded product. There are no particular limitations on the moisture, and wastewater discharged from various facilities in steelworks, or, if necessary, the above wastewater that has been treated to a state suitable for producing hydrated solids, can be used. Tap water, industrial water, etc. can also be used as moisture.

The binder is a hydraulic material that binds the steel slag as aggregate through a hydration reaction. Such binders can be powdered blast furnace slag, cement, silica fume, fly ash, or other powdered materials. Of these, it is preferable to use blast furnace slag powder as the binder. An example of blast furnace slag powder is blast furnace slag powder for concrete as specified in JIS A 6206:2013.

The alkaline stimulant is used in combination with a binder as necessary. The alkaline stimulant creates an alkaline environment and can promote the hardening of the hydraulic binder, thereby improving the strength of the hydrated solidified body produced. Examples of such alkaline stimulants that can be used include powdered lime powder, hydrated lime, and cement (e.g., ordinary Portland cement, blast furnace cement). Note that cement can function not only as an alkaline stimulant but also as a binder.

In the present invention, it is possible to use only the binder without using the alkaline stimulant, but it is preferable to use both. In particular, when using ground granulated blast furnace slag as the binder, it is preferable to mix cement as an alkaline stimulant. This allows the alkaline stimulant to create an alkaline environment and promote the hardening of the hydraulic binder, making it possible to more stably obtain high strength in the produced hydrated solidified body.

The steelmaking slag prepared as described above, water, a binder, and an alkaline stimulant that is added as needed can be mixed using a mixer. For example, a mixture can be produced by supplying steelmaking slag, cement as an alkaline stimulant, ground granulated blast furnace slag as a binder, and water to a mixer and mixing them. Additives may be added to the mixture as needed.

In the kneading process, the moisture content of the raw materials (i.e., steel slag, moisture, binder, and alkaline irritant if necessary) is measured during or before kneading, and the amount of moisture to be mixed is adjusted based on the measured moisture content. If the moisture content of the kneaded material is too high, i.e., if the moisture content is the same as that of conventional soft kneaded materials, the shape cannot be maintained after molding. If the moisture content of the kneaded material is too low, the hydration reaction does not proceed and the strength of the hydrated solidified body is not expressed. For this reason, the moisture content of the kneaded material is preferably 10% by mass or more and 14% by mass or less, and more preferably 12% by mass or more and 13% by mass or less.

Furthermore, the amount of powder (binder such as ground granulated blast furnace slag and alkaline stimulant such as cement) that is the base of the kneaded material is preferably 280 kg/ ^m3 or more and 440 kg/ ^m3 or less relative to the above moisture content. If the amount of powder is too much relative to the moisture content, the aggregate (steel slag) cannot be bound in the molding process described below, and the shape of the molded kneaded material cannot be maintained, or the kneaded material cannot fit into a formwork. On the other hand, if the amount of powder is too little relative to the moisture content, the fluidity is too high and the shape of the molded kneaded material cannot be maintained.

When using ground granulated blast furnace slag as a binder and cement as an alkaline stimulant, cement is expensive and emits a large amount of carbon dioxide during its production, making it an inferior raw material in terms of both cost and the environment. Therefore, it is desirable to reduce the proportion of cement and increase the proportion of ground granulated blast furnace slag. Specifically, the proportion of cement in the mixture is preferably in the range of 2% by mass to 14% by mass, and more preferably in the range of 2% by mass to 6% by mass. When the water content and the proportion of cement are within the above conditions, the proportion of steel slag in the mixture is 80% by mass to 88% by mass.

(2) Molding Step Next, the mixture produced in the mixing step is placed in a molding machine and molded to obtain a hydrated solidified body (molding step). The molding machine shown in Fig. 1 is equipped with a formwork, a pressure plate provided on the formwork, and a vibrator (not shown) provided on the formwork. An iron plate is placed under the formwork, and the mixture is then fed into the formwork, after which the pressure plate compresses the mixture and vibrates the formwork. This allows the mixture to be compacted in a short time by compression and vibration.

The molding machine can be any type of device, such as a vibrating type. The hydrated solid obtained by molding can be made to any size by changing the mold, but it is desirable to make each side approximately 100 mm to 300 mm, taking into account the need to feed it into a crusher. As an example, the hydrated solid can be molded to a size of 100 mm x 100 mm x 200 mm.

(3) Curing step In the present invention, it is preferable to further carry out a curing step of curing and drying the hydrated solidified body obtained in the molding step. This allows the hydrated solidified body to be dried further and its strength to be increased. For example, for the purpose of handling, the curing step may be composed of a step (primary curing step) in which the hydrated solidified body, which has been demolded from the molding machine by lowering the iron plate, is cured in a curing room for about half a day to harden the surface, and then the body is transported to a yard, and a step (secondary curing step) in which the hydrated solidified body is additionally cured in the yard for a maximum of one month until a certain level of compressive strength is achieved, so that the particle size after crushing becomes the expected particle size.

Thus, according to the present invention, since the hydrated solidified body is produced by molding the kneaded material with a molding machine, it is possible to produce the hydrated solidified body in a smaller space than the conventional technique described in Patent Document 1, in which the kneaded material is poured into a raw material yard and solidified. Specifically, for example, when producing 10,000 tons of hydrated solidified body every month, the conventional technique requires a space of about 20,000 to 40,000 ^m2 for the casting site, the roughly crushed product storage site, and the main crushed product storage site, excluding the roadbed material storage site for the final product. In contrast, the method according to the present invention makes it possible to produce the hydrated solidified body and the roadbed material described below in a space of about 10,000 ^m2 .

In addition, according to the present invention, the size of the hydrated solid formed by the molding machine can be adjusted, so by forming it to a size that can be fed into the crusher, operations such as cutting and rough crushing are not required, and the hydrated solid can be easily produced.

Furthermore, according to the present invention, due to the characteristics of the molding method, the proportion of steel slag in the mixture, which serves as aggregate, can be increased compared to the method of pouring the mixture into a raw material yard and solidifying it. Specifically, since steel slag can be mixed at a proportion of 80 mass% or more, it is possible to process a large amount of fine steel slag that has no use, and the fine steel slag can be effectively used as a roadbed material.

In this way, a hydrated solid can be produced.

(Method of manufacturing roadbed material)
Next, a method for producing a roadbed material according to the present invention will be described. The method for producing a roadbed material according to the present invention includes a crushing step for crushing the hydrated solidified material produced by the above-mentioned method for producing a hydrated solidified material according to the present invention into crushed particles, and a particle size adjustment step for adjusting the crushed particles to a required particle size.

(4) Crushing Step The hydrated solid obtained in the molding step or the hydrated solid that has been subjected to the curing step is crushed into crushed particles (crushing step). Crushing of the hydrated solid can be carried out using a crusher. As the crusher, a known crusher such as a cone crusher can be used. The "required particle size" is, for example, 40 mm or less.

(5) Grain Size Adjustment Step Next, the crushed particles obtained in the crushing step are adjusted to a required grain size to obtain a slag roadbed material (grain size adjustment step).

(6) Mixing process If necessary, the crushed particles whose particle size has been adjusted in the particle size adjustment process may be mixed with other materials to obtain a slag roadbed material (mixing process). Examples of other materials to be mixed with the crushed particles include steel slag and concrete rubble.

In this way, slag roadbed material can be produced.

According to the manufacturing flow shown in Figure 1, hot metal dephosphorization slag as the steelmaking slag, industrial water as the moisture, ground granulated blast furnace slag as the binder, and ordinary Portland cement as the alkaline stimulant were prepared, and these were fed into a kneading machine and kneaded to produce a kneaded product (kneading process). The kneaded product was then placed in a molding machine and molded to obtain a hydrated solidified body with a size of 100 mm x 100 mm x 200 mm (molding process). The composition of the obtained hydrated solidified body is shown in Table 1. Images of the obtained hydrated solidified body are also shown in Figures 2 and 3.

Next, the obtained hydrated solidified body was crushed in a crusher to produce crushed particles (crushing process). The crushed particles of the obtained hydrated solidified body were adjusted to the required particle size (particle size adjustment process), and then the particle size-adjusted crushed particles were mixed with hot metal dephosphorization slag and converter slag as steelmaking slag, and concrete rubble to obtain a slag roadbed material (mixing process). In this way, the hydrated solidified body and slag roadbed material were produced.

The moisture content of the hydrated solidified body is greatly affected by the moisture state of the steelmaking slag, which is the aggregate. However, when the steelmaking slag mixing ratio was set to 80% by mass or more and 88% by mass or less, it was possible to produce a hydrated solidified body that did not crumble after molding, as shown in Figures 2 and 3.

Figure 4 shows the particle size distribution of the crushed particles obtained by crushing the hydrated solid of Mixture 1 in a crusher, and the steelmaking slag used to produce the hydrated solid. As is clear from Figure 4, the particle size distribution was improved by hydrating the steelmaking slag, which was mainly 0-5 mm in size, into a hydrated solid.

Figure 5 shows the particle size distribution of slag roadbed material produced using the hydrated solidified material of Mix 1. As shown in Figure 5, by hydrating and solidifying the fine slag that is surplus to the particle size standard of RC-40 roadbed material, it is possible to recycle it as RC-40 roadbed material. The mixing ratio of the hydrated solidified material is determined by its relationship with other materials, but is not limited in the present invention.

According to the present invention, a hydrated solidified material can be easily produced even in a small space, and a slag roadbed material can be produced from the hydrated solidified material.

Claims (6)

A kneading step of kneading steelmaking slag, moisture, and a binder to prepare a kneaded mixture;
a molding step of putting the prepared kneaded mixture into a molding machine and molding it to obtain a hydrated solidified body;
A method for producing a hydrated solidified body comprising the steps of: The method for producing a hydrated solidified body according to claim 1, wherein the moisture content of the kneaded material is in the range of 10% by mass to 14% by mass. The kneaded product is a mixture of ground granulated blast furnace slag as the binder and cement that promotes hardening of the ground granulated blast furnace slag,
The method for producing a hydrated solidified material according to claim 1 or 2, wherein a mixing ratio of said cement in said kneaded mixture is in the range of 2% by mass or more and 14% by mass or less. The method for producing a hydrated solidified body according to claim 1 or 2, wherein the mixing ratio of the steel slag in the kneaded mixture is in the range of 80% by mass to 88% by mass. The method for producing a hydrated solidified body according to claim 1 or 2 further comprises a curing step of curing and drying the hydrated solidified body obtained in the molding step. A crushing step of crushing the hydrated solidified material produced by the method for producing the hydrated solidified material according to claim 1 or 2 into crushed particles;
A particle size adjusting step of adjusting the crushed particles to a required particle size;
A method for producing a slag roadbed material comprising:

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